As described in U.S. Pat. No. 6,186,701 to Kempers for example, which is hereby incorporated herein for all purposes by this reference, geotextile tubes are elongate flexible containers made of textile fabric and have been used as the core or base of a dam, a quay, a bank reinforcement, at the bed of a waterway, etc. and for dewatering sludge and other purposes.
Many dredged soils cannot be used where load bearing is required. Indeed, a conventional type geotube cannot reach any significant elevation when attempts are made to fill the geotube with silts, clays and organic matter. Designs for causeways have used geotubes stacked on the outside to act as the slopes protecting the roadways that are filled with dredged material. However, the soils constituting the dredged material that can fill the geotubes must be selected from soils capable of providing stability to those slopes, and this requirement often disqualifies some materials in close proximity to the location from being dredged to fill the geotubes.
Because of the natural tendency of the settling of the many tons of materials in slurry form that are pumped under pressure into geotextile tubes during their deployments alongside shorelines and other areas for which erosion protection is desired, the height of such geotextile tubes when filled with solids becomes limited by the circumference of the geotextile tube and the nature of the solids, all other parameters being equal. Moreover, geotextile tubes filed to their maximum natural height or close to that height tend to be relatively unstable and therefore pose safety issues if the solids might shift due to some environmental influence for example. Furthermore, instead of having a uniform transverse shape, when such conventional geotextile tubes are filled with solids that have been pumped into them, they also often are misshapen and resemble the form of undulating snakes with transverse shapes that vary all along the lengths of the geotextile tubes.
Increasing the maximum height at which large scale geotextile tubes of a given circumference and filled with solids of a given nature remain stable has been a vexing problem, the solution of which potentially capable of yielding many advantages.
The use of geotubes for filtering large amounts of liquid-solid matter has placed focus on the filtering characteristics of the fabrics used to construct the geotubes. For example, the fabric used to dewater coal sludge will have different filtering characteristics than the fabric used to de-water human waste. Moreover, the use of geotubes for de-watering sludge and filtering all types of waste, including food processing, animal and human etc., has created a demand for larger and stronger geotubes. To meet this demand, the strength of the fabrics used to make the geotubes has been increased. This increase in fabric strength has been attained by increasing the volume and density of the yarns per unit of length of the fabric and by using bulkier yarns. However, the attainment of increased strength in this manner results in undesirable changes in the filtering characteristics of the fabric.